The invention concerns thread-delivery devices of the type including a storage body comprising two axially-spaced sections. The first section is formed by bars forming a polygon around which thread is looped tangentially. The looped thread is advanced from the first section to a second section by a member having grooves. Thread is subsequently removed from the second section and is delivered to a machine, such as a weaving machine.
In prior devices of this type (see, for example, Swiss Patent Document No. 641 119), thread is advanced by means of threading grooves having face areas formed by spindles which are disposed in the space between two polygonal bars in such a way that the bottom of the threading grooves forms part of the polygon. Consequently, the entering thread is supported both by the polygonal bars and by the bottom of the respective threading groove and is configurated in polygonal form. Such thread-delivery devices are unsuited as a practical matter for installations in which the primary concern is making a thread available for uniformly tensioned withdrawal at high speed, for instance, for insertion in the weft compartment of a weaving machine. The reason for this is that the circumferential length of the second section onto which the thread windings are transferred pending their withdrawal is smaller than that of the first section where the thread loops formed by the threading grooves are of necessity of a circumferential length sufficient to pass around the individual bars of the polygon. Any considerable difference in the circumferential length of the first section from the circumferential length of the second section precludes extensive transfer of thread windings from the first section to the second section and their transport forward from the rear, while retaining the existing order of thread windings.
One different form of delivery device for weft threads, or the like, which provides an orderly arrangement of thread windings is disclosed in German patent document No. 2,035,754. However, an orderly arrangement of the thread windings side-by-side on the second section in a thread-delivery device of the type shown in Swiss Pat. No. 641,119 can be accomplished only to the extent that the thread windings slide due to sufficient inclination of the polygon bars toward the front end, i.e., due to the truncated cone-shaped extension of the polygon bars on the second section increasing considerably further the excess length of each thread winding relative to the circumferential length of the polygon bars. But this limits the use of such thread-feeding devices to applications where the thread is continually delivered in a loose form, for instance, for subjecting the yarn later to specific yarn treatments, such as vaporization. Moreover, the storage, arrangement and drive of the spindles arranged between polygonal bars is very expensive and leads to a design which is susceptible to malfunction. Furthermore, it is difficult to incorporate the thread windings which are still contained on the first section into the available thread supply.
In other thread-delivery devices which are geared to withdrawing the thread overhead, for instance, for feeding to circular knitting machines and looms (see German patent disclosure No. 2,003,760), a central cylindrical threaded body is combined with a rotatably mounted fork body; the bottom of the threading grooves of the central body and the outside surface of the fork prongs of the rotatable fork body form a polygon around which the thread is looped. There is no transfer of thread from a first section to a second section. In such devices, the achievable looped thread supplies are relatively small, limiting the application to withdrawing machines which always require only relatively short thread lengths.